Effect of hemorrhage on arterial plasma renin activity in the rabbit

Arterial plasma renin activity in the rabbit was measured at the beginning and end of a brisk hemorrhage and 40 min later. Activity rose to a mean of two and one-half times the control value during the hemorrhage, and was five times greater than the control 40 min later. The rise in plasma renin activity was not due to anesthesia, as light pentobarbitone produced no change. Conscious rabbits, severely bled from a carotid cannula, 2 to 5 hr after an ether anesthetic, also showed an increase in plasma renin activity at the end of hemorrhage. Forty-eight hours after both kidneys had been removed, renin activity was virtually absent and did not rise after hemorrhage.

A sensitive method for assay of plasma renin activity

Renin activity is separated from rabbit plasma by globulin precipitation, dialysis, and DEAE cellulose column chromatography with a Tris chloride buffer system and acid elution, followed by ultrafiltration. The plasma renin extract contains no renin substrate and no angiotensinase activity can be detected after incubation with angiotensin for 200 hr. Incubation with a known concentration of rabbit renin substrate, similarly free of renin activity and angiotensinase, at pH 6.0 in 0.1 M phosphate buffer forms angiotensin-like activity at a constant rate for up to 200 hr. Recovery and reproducibility are satisfactory. Evidence is presented that the material in the plasma extract behaves similarly to renin and that the incubation product is indistinguishable from angiotensin.

The preparation of rabbit renin-substrate for the assay of minute amounts of renin

1. By DEAE-cellulose chromatography and treatment with Cd(2+) a partially purified renin-substrate has been prepared from rabbit serum. 2. It has the following properties: (a) Angiotensinase activity is undetectable: 0.1mug. of angiotensin was recovered intact after incubation with the substrate at 37 degrees for 200hr. (b) It does not contain renin and does not generate vaso-active substances when incubated alone. (c) It is ten times as active as serum in terms of angiotensin produced/mg. of protein. (d) It has not deteriorated after storage for 3 months at 4 degrees at pH7.5.